linux-kernel - [PATCH 2/6] nvmem: imx-ocotp-ele: fix reading from non zero offset

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Message-Id: <20241230141901.263976-3-srinivas.kandagatla@linaro.org>
Date: Mon, 30 Dec 2024 14:18:57 +0000
From: srinivas.kandagatla@...aro.org
To: gregkh@...uxfoundation.org
Cc: linux-kernel@...r.kernel.org,
	Sascha Hauer <s.hauer@...gutronix.de>,
	stable <stable@...nel.org>,
	Peng Fan <peng.fan@....com>,
	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: [PATCH 2/6] nvmem: imx-ocotp-ele: fix reading from non zero offset

From: Sascha Hauer <s.hauer@...gutronix.de>

In imx_ocotp_reg_read() the offset comes in as bytes and not as words.
This means we have to divide offset by 4 to get to the correct word
offset.

Also the incoming offset might not be word aligned. In order to read
from the OCOTP the driver aligns down the previous word boundary and
reads from there. This means we have to skip this alignment offset from
the temporary buffer when copying the data to the output buffer.

Fixes: 22e9e6fcfb50 ("nvmem: imx: support i.MX93 OCOTP")
Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
Cc: stable <stable@...nel.org>
Reviewed-by: Peng Fan <peng.fan@....com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
---
 drivers/nvmem/imx-ocotp-ele.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/nvmem/imx-ocotp-ele.c b/drivers/nvmem/imx-ocotp-ele.c
index 2e186b7d3b04..b2d21a5f77bc 100644
--- a/drivers/nvmem/imx-ocotp-ele.c
+++ b/drivers/nvmem/imx-ocotp-ele.c
@@ -71,12 +71,14 @@ static int imx_ocotp_reg_read(void *context, unsigned int offset, void *val, siz
 	u32 *buf;
 	void *p;
 	int i;
+	u8 skipbytes;
 
 	if (offset + bytes > priv->data->size)
 		bytes = priv->data->size - offset;
 
-	index = offset;
-	num_bytes = round_up(bytes, 4);
+	index = offset >> 2;
+	skipbytes = offset - (index << 2);
+	num_bytes = round_up(bytes + skipbytes, 4);
 	count = num_bytes >> 2;
 
 	p = kzalloc(num_bytes, GFP_KERNEL);
@@ -100,7 +102,7 @@ static int imx_ocotp_reg_read(void *context, unsigned int offset, void *val, siz
 			*buf++ = readl_relaxed(reg + (i << 2));
 	}
 
-	memcpy(val, (u8 *)p, bytes);
+	memcpy(val, ((u8 *)p) + skipbytes, bytes);
 
 	mutex_unlock(&priv->lock);
 
-- 
2.25.1